Beds used in hospitals, other health care facilities and home health care settings may be equipped with a climate management topper which manages the temperature and humidity in the immediate vicinity of a bed occupant. The topper may be integrated with a mattress or may be a separate component placed atop the mattress. A typical topper includes a liner which has a lower panel facing away from the occupant and an upper panel facing toward the occupant. In some cases the upper panel is liquid permeable. The liner panels define an interpanel interior space. The topper also includes a gas inlet for admitting gaseous fluid into the interior space and a gas outlet for exhausting the gaseous fluid from the interior space. A blower is connected to the topper inlet by a gas supply conduit. A spacer material occupies the interior space. The spacer is fibrous or mesh-like and therefore porous enough to permit gas flow through the topper interior space from the gas inlet to the gas outlet. During operation the blower propels a stream of coolant, usually ambient air, through the interior space from the inlet to outlet. Accordingly the interior space serves as a fluid flowpath. The fluid stream helps cool the skin of the bed occupant and carry away any occupant perspiration or other liquid which migrates across the liquid permeable upper panel. Both the cooling and the liquid transport are desirable to help resist the formation of pressure ulcers on the occupant's skin. The portions of an occupant's anatomy that bear heavily on the topper are the sites most susceptible to the development of pressure ulcers. Assuming the occupant is supine, these sites may include the occupant's shoulder blades, buttocks, elbows and heels. Therefore these are sites where targeted, preferential climate control would be most beneficial for resisting the formation of pressure ulcers.
The spacer exhibits some degree of crush resistance but nevertheless becomes compressed and therefore denser where it bears the weight of the occupant. This increased density locally increases resistance to airflow and therefore causes diversion of some of the coolant air to other portions of the flowpath where the occupant's weight is not bearing as heavily on the topper. As a result less coolant flows under the heavily loaded parts of the occupant's body, which are the portions most susceptible to pressure ulcers, while more coolant flows underneath the portions of the occupant's body that are more lightly loaded and therefore less susceptible to pressure ulcers. This is opposite what is needed.
One way to achieve better targeted climate management is described in US 2013/0212808 (application Ser. No. 13/401,401) which describes a flowpath shaped to preferentially direct coolant to where it is predicted to be most needed. Yet another way to achieve better targeted climate management is described in US 2013/0205506 (application Ser. No. 13/396,224) which describes a flowpath with nonuniform resistance to preferentially drive coolant to where it is predicted to be most needed. These systems offer simplicity, but are “one size fits all” solutions that cannot readily accommodate patient specific needs such as directing coolant to account for the exact position of the patient on the topper and to account for which portions of the occupant's anatomy are most needful of climate management at any given time. Another way to focus the coolant on the most susceptible sites is described in U.S. Pat. No. 8,327,477 which describes a system in which a controller activates selected thermally conductive pathways in response to information from a detector, such as an array of pressure sensors. Although this system can provide patient specific targeted cooling and can respond to changing requirements, it requires certain components that are not ordinarily used with conventional climate management toppers (e.g. the thermally conductive pathways, the pressure sensors, and a set of thermoelectric modules) as well as software to control system operation.
It is, therefore, desirable to provide a climate management system that is occupant specific (e.g. responsive to the occupant's position and responsive to which portions of the occupant's body are most susceptible to pressure ulcer formation at any given time). It is also desirable for such a system to be passive, i.e. to not require a controller.